Circuit breaker



1959 B. A. PlTEO, JR., ETA]. 2,912,545

CIRCUITQBREAKER Filed Nov. 21, 1958 INVENTORS BENJAMIN A. Pm-zo UR,

DAVID B. Powzu.

A TTDRNEY works.

United States Patent H 2,912,545 a CIRCUIT EREAKER Benjamin Anthony Piteo, 'Jr., Forestville, and David B. Powell, Bristol, Conn, assignors to General Electric Company, a corporation of New York ApplicationNoveniber 21 19 58, Serial No. 775,618

6 Claims. (Cl.'200 -109) This invention relates to electric circuit breakers and particularly to electric circuit breakers of the type used for controlling power distribution and secondary net- Still more particularly, the invention relates to electric circuit breakers of the type having provision for causing automatic opening by remotely disposed control means of the relay or other suitable type. I

Electric circuit breakers of the type comprising a molded insulation casing usually incorporate means for causing the contacts of the circuit breaker to open automatically upon th e occurrence of high or excessive current conditions in the circuit controlled by the breaker.

shunt tripping means to effect automatic opening, not only upon the occurrence of excessive current conditions I in the controlled circuit but also in response to the operation of a remote control device such as a switch or relay, In accordance with the prior art, auxiliary tripping .means have been'provided in the form of a magnetic solenoid type device which is operated in response to the operation of a remote controldevice. These prior art devices, however, have been relatively large, bulky and expensive, and not usable in circuit breakers of relatively compact design. Furthermore, they have not been suit- -able fr installation by the user but have required for their installation skills and tools which are to be found only in the plant of the manufacturer of the circuit breaker itself because of the necessity for mounting essential parts and adjusting them with relation to the other parts of the mechanism and to each other.

It is an object of the present invention to provide a shunt trippingdevice which is small, reliable andinexpensive andwhich can be readily added to a conventional circuit breaker by a relatively unskilled employee ofthe user without any tools other than an ordinary screwdriver and hammer.

It is another object of the invention to provide a shunt tripping device adapted for use in compact type circuit breakers where mounting space is extremely limited.

i ,Another object of the invention is to provide a device having a basic construction of which the essential parts are readily adaptable for use with circuit breakers equipped with tripping devices either of the pull type or the push type.

I In carrying the invention into effect in one form thereof, anelectric circuit breaker is provided including a main insulating casing, a pair of relatively movable contacts ,In such circuit breakers operating mechanism is provided member movable to cause automatic opening of I i I 2,912,545 Patented Nov. 10, 1959 in the casing, operating means for operating the movable contacts between open and closed circuit positions including a pivoted contact operating arm and a trip unit comprising a separate insulating housing containingha te mechanism. V a

A shunt tripping device is provided including a solenoid and an auxiliary switch connected in series with the solenoid. These parts are mounted and arranged in the [circuit breaker so that thesolenoid, the switch, and the pivot of the movable contact arm are substantially in vertical alignment between the 'top and bottom of "the main casing, adjacent the trip unit housing. The solenoid is'provide'd'with'an extension disposed to extend into the trip unit h'ousi'ng and to operate'the trip unit upon energization of the solenoid to cause automatic opening movement of the operating mechanism. Resilient operating means is also provided, disposed to be operated by the 'movable contact armup'on its movement toward open circuit position, for operating the auxiliary switch to deenergize the solenoid.- The auxiliary switch is, moreover, r'nounted'in an inverted position, with its actuator 'dirccted toward the contact arm so as to be more readily operated thereby. V V

For a better and more complete understanding of the invention, reference should now be had to the following specification and to the accompanying drawing in which:

Figure 1 is1a'side eelvation view of a portion of an electric circuit'b'reaker incorporating the invention with a portion ofthe sidewall being broken'away to reveal certain details of the tripping mechanism and also to"rev'e al an assembly of stationary and movable contacts together with a pivoted carrying arm for themovable contact member of the assembly;

Figure 2 is a" sideelevation view of'a portion ofthe mechanism of Figure: 1 showing the parts ina diifere'nt position from 'thatoccupiedin Figure '1;

'Figure 3 is a view similar to Figure 2 but'showinga modified form of the invention.

Referring now *to the drawing and particularly to Figure 1, an electric circuit breaker is provided with-an insulating casing having a base land a cover platel.

Mounted on the base area plurality of relatively stationary contact assemblies 3, of which only oneis shownfand a plurality of cooperating movable contact assemblies" ibf which 'is shown only that one which coacts with the stationary contact assembly 3. Themovable conta'cfzissembly 4 is pivotally mounted in the casing base Ion a *pivotal shaft 5. "*All movable contact assemblies are ganged together/for movement in unison by a contact cross arm 6 to which each of the movable contact assemblies 4 is attached by suitable means such asian inverted U-shaped bracket 7. The movable contact members themselves are electrically connected by suitable means such as a flexible braid 8 to a "terminal (not shown) of atrip unit 9 which has its other terminal (also notshown) connected to relatively stationary terminal connecting lugs'for' connection to incoming powerlines.

The trip unit 9 includes a movable trip bar10 which is pivotally supported by pivot means 11 within the casing 12 of the trip unit. Preferably, this trip unit casing isalso "made of a moldedinsulating material. The trip baris arranged to be moved on its'pivot by suitable current responsive means such, forexample, as the bimetallic strip 13 which may be heated by current carrying means included in'the electrical circuit which is controlledby the main contact assemblies 3 and 4. .This trip unit is'arranged to effect release of a mechanism retaining latch (not shown) to cause automatic opening of the circuit breaker contacts in aconventional and well understood manner. A showing ofthe retaining latch is omitted "sincean' understanding 'of the details of this element and and closed position.

The construction of the trip unit 9 and the contact operating mechanism may be of any suitable type. For the purpose of causing actuation of the trip bar 10 by remote control in response to the operation of some remote device such as a switch or relay, shunt trip means in the form of an accessory attachment 16 is provided which may readily and easily be installed on the breaker in the field by relatively unskilled workmen. This accessory attachment comprises a suitably insulated stationary supporting bracket 17 rigidly secured to the insulating casing 12 of the trip unit 9 by suitable means such as screws 18. To mount the device, a knockout portion in the trip unit housing is removed to provide an opening through which the extension 20a is passed to engage and rotate the trip' extension of the plunger between the right-hand (as seen in Figure 1) end wall of the magnetic frame and a retaining washer 22 which is suitably secured to the end of the plunger extension as by riveting or other suitable means. As shown in Figure 1, the spring biases the plunger to the right. Mounted within the magnetic frame and surrounding the plunger 20 is an energizing coil 23 which is provided with leads 24 for connection to a suitable power source. The opposite end of the plunger which is in the form of a cylindrical extension 20a extends through an opening in the wall of the trip unit 9 to within a short clearance distance of the right-hand (as seen in Figure 1) surface of the pivoted bar 10. Energization of the operating coil 23 attracts the plunger toward the left and forces the cylindrical extension into engage- 4 free end of the resilient member is in close proximity to the push button operator 25c.

In operation, energization of the operating coil 23 by means of a remote control device such as a switch or relay attracts the plunger to the left (as viewed in Figure 1) toward the solenoid pole face. This causes the cylindrical extension 20a to engage the trip bar 10 and to rotate it in a counterclockwise direction about its pivot. This in turn rotates the circuit breaker trip shaft and allows the circuit breaker to trip open. As the movable contact arm rotates to the contact open position illustrated in Figure 2, the inverted U-shaped bracket 7 on the cross bar 6 engages the free end extension of the resilient operating member 27 and deflects it from its normal position into engagement with the push button operator. This results in opening the normally closed contact of switch 25 thereby to deenergize the operating coil 23 of the solenoid. Following deenergization of the solenoid, the spring 21 returns the plunger to its original reset position in which it is shown in Figure 1.

In the modified form of the invention which is illustrated in Figure 3, the parts within the trip unit 9 are so arranged that the trip bar 10 is rotated in a clockwise direction to trip the breaker. This arrangement requires the solenoid to exert a pull on the end of the trip bar instead of a push. Consequently, it is turned end for end from the position shown in Figure 1, and it is mounted to a rectangular shaped insulating block 28 which in turn is ment with the trip bar to cause it to move about its pivot prises an insulating casing formed of two matching insulating halves retained together by suitable means such as rivets. It includes relatively movable cooperating con tacts electrically connected to terminals 25a and 2511. Its movable contact is biased to one side of its pivot by an overcenter leaf spring and is adapted to be moved to the other side by the push button operating member 250. The construction and arrangement of the switch are such that in the absence of any actuating force on theoperat ing member 250 the switch contacts are closed thereby partially to complete an energizing circuit for the operating coil 23 through leads 24 to a suitable source. Upon inward movement of the operating member, the movable contact member suddenly snaps overcenter to the open circuit position to interrupt the energizing circuit.

As shown, the miniature switch 25 is secured to a mounting bracket 26 which in turn is secured by screws or other suitable means to the pole surface of the magnetic frame of the solenoid which faces the trip unit 9. Sandwiched between one leg of the bracket and the pole face is a resilient operating member 27 which is formed with a double bight of such shape that with the circuit breaker closed as illustrated in Figure 1, the free end of the resilient member occupies a position between the push button operation 250 and the inverted U-shaped bracket 7 which secures the cross arm 6 to the movable circuit breaker arm, The sharp angle of the bight closest to the secured to a mounting bracket 29. This mounting bracket 29 is mounted to the trip unit 9 by mounting screws or other suitable means. To the end of the plunger which is provided with the spring retaining washer 22 is mounted a hook member 31. To mount the solenoid assembly, a knockout in the trip unit must be removed so that the hook can be passed through it and located to pick up and rotate the trip bar.

To the end of the solenoid remote from the spring, the auxiliary switch 25 is mounted by means of a mounting bracket 32. The mounting bracket 29 which mounts the solenoid assembly to the trip unit is dimensioned so that the auxiliary switch when secured to the mounting bracket 32 is located generally in the space between the cross bar 6 and the movable assembly 4 of the circuit breaker. For actuating the push button operator of the auxiliary switch, a U-shaped resilient switch actuator 33 member is provided. One of its legs is riveted or secured by other suitable means to the movable contact carrying arm of the circuit breaker in such position that when the breaker is opened, the free end of the resilient operator engages the push button operator of the auxiliary switch to cause it to open its contacts and deenergize the solenoid.

In operation when the solenoid coil is energized by closing its energizing circuit at remote contacts, the solenoid plunger rotates the breaker trip bar 10 to trip the breaker. In the tripped position of the breaker, the flexible switch actuator 33 operates the auxiliary switch 25 to interrupt the energizing circuit of the operating coil of the solenoid. The spring 21 returns the hook member to its original position.

It will be observed that the shunt tripping solenoid 16, the auxiliary switch 25, and the contact-bar cross-arm 6 and bracket 7 are all disposed within the circuit breaker casing substantially in vertical alignment, one above the other. This provides the most compact arrangement of these components possible. Moreover, the auxiliary switch 25 is preferably oriented with its actuator 25c directed downwardly, so that movement of the portion of the operating mechanism located directly thereunder may readily be utilized to operate the switch 25. This operation is preferably achieved by a novel arrangement comprising a resilient strip which permits relative substantial movement of the operating agency after the strip has engaged the switch actuator and even after actuation has taken place. This makes it unnecessary to perform critical adjusting operations on these components and facilitates their field installation.

Although, in accordance with the provisions of the patent statutes, this invention is described as embodied in concrete form and the principle of its operation has been explained together with the best mode in which it is now contemplated applying that principle, it will be understood that the specific structures shown and described are merely illustrative and that the invention is not limited thereto since alterations and modifications will readily suggest themselves to persons skilled in the art without departing from the true spirit of the invention or from the scope of the annexed claims.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric circuit breaker, a casing, a stationary contact mounted in said casing, a relatively movable contact in said casing, operating mechanism for operating said movable contact between open and closed circuit positions comprising a contact arm pivotally supported in said casing and a trip member, a solenoid having a movable core plunger disposed to engage said trip member, spring I means biasing said plunger out of engagement with said trip member, means for energizing said solenoid to effect movement of said plunger into engagement with said trip member, and auxiliary switch means having a rectilinearly movable actuating member disposed to be actuated by a portion of said operating mechanism upon circuit opening movement thereof, said solenoid and auxiliary switch means and said portion of said operating mechanism being disposed substantially in vertical alignment in said casing with said switch means between said solenoid and said portion of said operating mechanism.

2. In an electric circuit breaker,a main insulating casing having top and bottom walls, a stationary contact mounted in said casing, a movable contact arm pivotally supported in said casing, operating mechanism for said movable contact arm, a trip unit in said main insulating casing comprising an insulating enclosure extending substantially completely between said top and bottom walls of said main casing, said contact arm being pivotally supported in said main casing adjacent said bottom wall and adjacent said trip unit enclosure, shunt tripping means comprising a solenoid supported in said main casing adjacent said top wall and adjacent said trip unit enclosure, auxiliary switching means supported in said main casing adjacent said trip unit enclosure and between said solenoid and said contact arm pivot, trip-actuating means carried by said solenoid and extending into said trip unit enclosure for actuating said trip unit upon energization of said solenoid to cause opening movement of said operating mechanism and said contact arm, and resilient operatingmeans disposed to be operated by said contact arm upon movement thereof to open position for operating said auxiliary switch to deenergize said solenoid.

3. The combination as set forth in claim 2, wherein said auxiliary switching means comprises a switch having a rectilinearly movable actuator, said switch being disposed with said actuator directed toward said contact operating arm and away from said solenoid.

4. The combination as set forth in claim 3 wherein said resilient operating means comprises an elongated strip of resilient material having one end thereof attached to one of said solenoid and said contact operating arm and having a deformable portion remote from said attached end, said deformable portion being disposed to engage said switch actuator when said strip is operated by said contact arm.

5. For use with a circuit breaker having a casing, a stationary contact mounted in said casing, a relatively movable contact assembly comprising a pivotally mounted contact carrying arm and a movable contact mounted thereon, operating mechanism for operating said movable contact between open and closed positions and a trip member, an attachment comprising a solenoid having a supporting frame, a movable armature provided with an extension disposed to project into proximity with said trip member, spring means biasing said armature in a direction to retract said extension away from engagement with said trip member, means for energizing said solenoid to effect movement of said extension into engagement with said trip member, and switching means mounted on said supporting frame and having a rectilinearly movable plunger type operating member, and an actuator therefor comprising a strip of resilient thin metallic material mounted on said frame and having a free end in close proximity to the pivot of said arm and disposed to be I engaged by said arm to engage and operate said operating member to deenergize said solenoid in response to the circuit opening movement of said arm.

6. For use with a circuit breaker having a casing, a stationary contact mounted in said casing, a relatively movable contact assembly comprising a pivotally mounted contact carrying arm and a movable contact mounted thereon, operating mechanism for operating said movable contact between open and closed positions and a trip member, an attachment comprising a solenoid having a supporting frame, a movable armature provided with an extension disposed to project into proximity with said trip member, spring means for biasing said armature in a direction to retract said extension away from engagement with said trip member, means for energizing said solenoid to effect movement of said extension into engagement with said trip member and switching means mounted on said frame and having a rectilinearly movable plunger type operating member, and an actuator therefor comprising a U-shaped strip of resilient thin metallic material having one of its legs mounted on said contact carrying arm in close proximity to its pivot and disposed in position to effect engagement of its free leg into engagement with said operating member to deenergize said solenoid in response to the circuit opening movement of said arm.

References Cited in the file of this patent UNITED STATES PATENTS 1,772,442 Hanny Aug. 5, 1930 

